Bad customer service

My sim card was not work king for over 12 hours, when people call me sometimes it would state that the number does not exist. It didn't allow me to make calls or receive. I couldn't even register any network manually and even try to roam it did not work. I went to a cell c shop.and they advise me to buy a new sim and make a sim swap because they also didn't know what's the problem with the sim card. So I bought a sim but after i left the shop the sim card started working again so worried that it might happen again and i will miss important calls i called to make a sim swap but a consultant by a name of Phumzile was not helpful, she treated me like as if i dont know how to use my cell phone. She ended up by telling me that she will lunch a case so seeing that she does not want to help me I asked her to give me a case number, she to me that she will send. She did not send anything and i haven't received a call from cell c which means she was just telling me that so i can hang up